A ranged set is an ordered list of ranges. this allows sets such as all reals x such that: (0.25 < x <= 0.75 or 1.4 <= x < 2.3 or 4.5 < x)

alternatively you can have all strings s such that:

("f" <= s < "g")
this package provides the documentation for a library for the haskell programming language. see http://www.haskell.org/ for more information on haskell.